Electrical terminal



.iy EL 1940. R N. ROWE ET AL ELECTRICAL TERMINAL Filed larch 12, 1938 g 7 WWW gm \w E w w x v f, Wm fi my fl F i m B Y I 1 AT RNEY Patented May 21, 1940 Raymond N. Rowe, Plainvillc,

ELECTRICAL TERMINAL and John L. Robertson, Forestville, Conn., assignors to The Trumbull Electric Manufacturing Company, Plainville, Conn., a corporation of Connecticut Application March 12, 1938, Serial No. 195,488

2 Claims. (Cl. 173-269) Our invention relates to devices for connecting wires or cables.

The main object is to provide a rugged terminal with effective clamping means, the parts of which can be readily assembled.

A special object is to provide means for connecting the rotatable clamp screw or nut and the clamp shoe so that they can be assembled and handled as a unit and removed as a unit from the housing or body.

Another object is to provide a device of this character in which the clamp shoe is movable with the threaded nut and can be readily released and retracted from the cable or entirely removed from the housing or terminal.

Fig. 1 is a longitudinal sectional view of one form of terminal involving our invention.

Fig. 2 is a plan view of the same.

Fig. 3 is a cross sectional view of the same.

Fig. 4 is a sectional view of the clamp screw or nut.

Fig. 5 is an exploded perspective view of parts of the device.

Fig. 6 is a view of the underside of the clamp shoe or saddle showing a transverse rib which may be employed.

The main body or housing I of the device may be formed of a single piece of metal with a recess or passage 8 to receive the cable, conductor or circuit wire 9, which is quite frequently of the multi-strand type.

The diameter of the .recess will ordinarily be enough larger than the cable to conveniently recelve'it. It will be found however that the terminal will accommodate considerably smaller conductors.

The inner face l2 of the shoe Ill is preferably concave so as to embrace the top and sides of the cable. The clamp screw or nut I3 is adjustable in the threaded socket it in the terminal body and presses against the clamp shoe III to force it against the conductor 9.

The axis of the passage or socket l4 intersects the axis of the cable or conductor recess 8 and the walls of the passage l4 and recess 8 are uninterrupted circumferentially around the mouth of each. The side walls of the screw threaded passage ll are continued into the recess 8 in the form of grooves H to accommodate the screw and the side extensions of the clamp shoe l and permit the shoe to be inserted into the passage l4 before the cable is inserted. This also allows the shoe to tilt slightly and accommodate itself in the passage to the cable end.

We have found, however. that it is highly desirable that the shoe be secured to the clamp screw not only for convenience in keeping the parts together in handling but also to facilitate retraction and removal of the shoe. As the result of considerable study and experimentation we have discovered a very simple solution of the problem.

The clamp screw l3 preferably has a central recess l for the insertion of a wrench. This recess extends through the screw and at the inner end a recess i6 of larger diameter is provided to receive the edge of and form a seat for a metal disc or washer IT. This disc may be secured to the clamp screw by swaging, spinning or staking a portion or portions I8 of the lower face of the screw over the edges of the disc. The rim IQ of the clamp screw extends slightly below the disc so that the solid part of the screw engages the upper face of the shoe I0 when the screw is tightened against it.

The clamp shoe or saddle is pivoted to the disc l1 and thus to the screw l3 by a pivot member 20 which passes through the central hole 2| in the shoe Ill and the central hole 22 in the disc ll. The upper edge of the hole 2| is preferably depressed or countersunk to receive the depressed central portion 23 of the disc so as to assist in aligning o'r centering the shoe and the screw and to prevent any pressure being transmitted to the disc. The pivot member 20 is preferably in the form of a rivet, the upper end of which fits loosely in the depressed center of the disc I1 and the lower end fits in a recess 24 in the under face of the shoe so that it will not interfere with the engagement of the shoe with the cable or conductor. The upper ends of the rivet member 20 are bent over in the depression in the disc H as shown in Figs. 1 and 2 so as not to project as far as the upper flat surface of the disc and so as to be clear of the end of any tool which may be inserted in the opening ii in the screw I3.

The depressed central portion of the disc and the countersunk portion of the hole 2| in the shoe or saddle ID are so arranged as to provide a free bearing for the shoe until the shoe is pressed hard enough against a cable to force the upper face of the shoe against the lower face of the clamp screw or nut l3 as'is necessary in order to securely clamp a cable in position. Thus all of the operating strain is taken up'by the clamp screw and the shoe or saddle.

The clamping action of this device is similar to that of the prior. Patent 2,068,152 but the improvements make it easier to handle as the shoe and screw are connected together and cannot be accidentally separated or mislaid.

It also has the great advantage of ease of retraction and removal. If the shoe is wedged or sticks in the housing or against the cable it may be loosened and withdrawn by the usual action of loosening and removing the clamp screw or nut.

For manufacturing reasons it is ordinarily preferable to make the clamp screw I 3 with a broached hexagon hole passing entirely through the screw and to provide the necessary bottom in the hole in the form of a separate disc as shown but the bottom of the hole may be closed in any suitable manner.

An important advantage of securing the saddle and the screw or nut together in this manner is that these parts are held together in alignment and thus cannot cock, wedge or jam while a cable is being secured in position in the lug and the pivotal connection allows the saddle or shoe to rotate sufficiently to align with the cable.

It will be noted that the body or housingis rugged and that the walls of the conductor recess at its entrance are continuous or undivided. The same condition will be found at the inner end of the recess. As a result the body has a maximum strength to resist the pressure of the clamp screw and shoe against the cable end. The screw passage also has a continuous or undivided wall surrounding it so as to afford maximum strength. These features are important as the parts should not be any heavier than necessary and yet must withstand considerable stress when a cable end is securely clamped in place.

We claim:

1. A solderless terminal lug having a body to be secured to a support, said body having a conductor cable recess and a screw threaded passage whose axis intersects the axis of said recess and grooves at opposite sides of the recess formed as continuations of the sides of the passage, the entrance side walls of said passage being continuous, a clamp screw adjustable in said passage, a thin disc having its edges clamped in the bottom of the screw above its lower surface and a clamp shoe pivoted to said disc and insertable into said screw threaded passage and movable up and down with said screw within said passage and having portions extending into said grooves, said screw itself having a bearing surface against said shoe and the shoe and disc being protectively positioned within said passage and said conductor recess.

2. A solderless terminal lug having a body to be secured to a support, said body having a conductor recess and a screw threaded passage whose axis intersects the axis of said recess and grooves at opposite sides of the recess formed as continuations of the sides of the screw threaded passage, the side walls of said passage at its mouth being continuous, a clamp screw adjustable in said passage and having a central recess for a wrench extending substantially to the bottom of the screw, a thin disc secured to the screw and closing the bottom of the wrench recess and a clamp shoe pivoted to said disc and insertable into said screw threaded passage and movable up and down with said screw within said passage and having portions adapted to extend into said grooves, said screw having a bearing surface against said shoe of substantially the diameter of said shoe, and the shoe being protectively positioned within said passage and said conductor recess.

RAYMOND N. ROWE. JOHN L. ROBERTSON. 

